This proposal represents a direct continuation of a research program designed to define the neural mechanisms responsible for the central and peripheral control of motor behavior. Recently we have described a new pattern of somatotopic and functional organization for the motor cortex. We have proposed that there are two spatially separated motor control systems within area 4 which deal with fundamentally different aspects of motor behavior. Our objective for the next grant period is to define the input-output organization of these two motor control systems. We will use both physiological and correlative anatomical methods for these studies. We hope that an analysis of motor cortex input-output organization from this new perspective will lead to a better understanding of the participation of the motor cortex in the central control of movement.